1. Field
An embodiment of the present disclosure relates to cathode active materials, cathodes including the cathode active materials, and lithium batteries including the cathodes, and more particularly, to cathode active materials having a high voltage and energy density, cathodes including the cathode active materials, and lithium batteries including the cathodes.
2. Description of the Related Art
A lithium metal phosphate has high stability when used as a cathode active material in a rechargeable battery. For example, since LiFePO4 has a strong Fe—P—O bond, oxygen does not leak even if an electrolyte battery is shortened or overheats.
A LiFePO4 material that has been widely used has excellent thermal stability and lifetime properties, but reduced energy density due to a low voltage of 3.4 V. On the other hand, a LiMnPO4 material has the same theoretical capacity as the LiFePO4 material and a voltage equal to or greater than 4.0 V, and thus the LiMnPO4 material has a theoretical energy density higher by 15% or more than the LiFePO4 material.
However, a structural change referred to as Jahn-Teller distortion occurs in a LiMnPO4 material due to Mn+3 ions generated during charging, and thus an actual capacity of the LiMnPO4 material is so low.